dynamic

class ExampleClass{    public ExampleClass() { }    public ExampleClass(int v) { }    public void exampleMethod1(int i) { }    public void exampleMethod2(string str) { }}

static void Main(string[] args){    ExampleClass ec = new ExampleClass();    // The following call to exampleMethod1 causes a compiler error     // if exampleMethod1 has only one parameter. Uncomment the line    // to see the error.    //ec.exampleMethod1(10, 4);这样调用报错    dynamic dynamic_ec = new ExampleClass();//这种情况编译时不检查错误 运行时检查错误    // The following line is not identified as an error by the    // compiler, but it causes a run-time exception.    dynamic_ec.exampleMethod1(10, 4);    // The following calls also do not cause compiler errors, whether     // appropriate methods exist or not.    dynamic_ec.someMethod("some argument", 7, null);    dynamic_ec.nonexistentMethod();}

任何对象都可隐式转换为动态类型，如下面的示例所示。                      
          
dynamic d1 = 7;dynamic d2 = "a string";dynamic d3 = System.DateTime.Today;dynamic d4 = System.Diagnostics.Process.GetProcesses();
反之，隐式转换也可动态地应用于类型为 dynamic 的任何表达式。                      
  
int i = d1;string str = d2;DateTime dt = d3;System.Diagnostics.Process[] procs = d4;
// Valid.ec.exampleMethod2("a string");// The following statement does not cause a compiler error, even though ec is not// dynamic. A run-time exception is raised because the run-time type of d1 is int.ec.exampleMethod2(d1); 参数错误 编译时不会检查因为 dynamic 类型 但是运行时会报错// The following statement does cause a compiler error.//ec.exampleMethod2(7);
  
class Program{    static void Main(string[] args)    {        dynamic dyn = 1;        object obj = 1;        // Rest the mouse pointer over dyn and obj to see their        // types at compile time.        System.Console.WriteLine(dyn.GetType());        System.Console.WriteLine(obj.GetType());    }}
  WriteLine   语句显示 dyn 和 obj 的运行时类型，此时，两者具有相同的整数类型。  将生成以下输出：  
        System.Int32  
        System.Int32                          
    
 若要查看 dyn 和 obj 之间的差异，请在前面示例的声明和 WriteLine 语句之间添加下列两行之间。                  
dyn = dyn + 3;obj = obj + 3;
 为尝试添加表达式 obj + 3 中的整数和对象报告编译器错误。  但是，不会报告 dyn + 3 错误。  编译时不会检查包含 dyn 的表达式，原因是 dyn 的类型为 dynamic。